Adding Textures to Glove Rig
The selection of the mesh is disabled, you need to enable it first. It's a 2.79 blend file and for some reason, the materials are not shown correctly in Blender 2.8+. But you can recreate them:


Add the Shading workspace: [+] → Sculpting → Shading
Click the Filter icon, and select the first 5 Restriction Toggles. This includes Selection, the arrow icon.
The mesh is parented to the armature. Expand it and look for CSGOMotogloves. Activate Selection (arrow icon). Now you can select the mesh. Select it.
Materials exist already. Select one to recreate
Check Use Nodes in the shading editor
Add the Image Texture nodes and the Normal Map node. Select the images for the Image Texture nodes. Don't forget to set Color Space to Non-Color for the normal map image.

Repeat steps 4 to 6 for the remaining 2 materials. That's it :-)